'And that's not all,' the Brainman continued. 'With some data compression, it could store not only the memories – but the actual person.'

'And reproduce them again?'

'Of course; straightforward job of nanoassembly.'

So I'd heard, Poole told himself – but I never really believed it.

Back in his century, it seemed wonderful enough that the entire lifework of a great artist could be stored on a single small disk. And now, something no larger could hold – the artist as well.

'I'm delighted,' said Poole, 'to know that the Smithsonian still exists, after all these centuries.'

'You probably wouldn't recognize it,' said the visitor who had introduced himself as Dr Alistair Kim, Director of Astronautics. 'Especially as it's now scattered over the Solar System – the main off-Earth collections are on Mars and the Moon, and many of the exhibits that legally belong to us are still heading for the stars. Some day we'll catch up with them and bring them home. We're particularly anxious to get our hands on Pioneer 10 – the first manmade object to escape from the Solar System.'

'I believe I was on the verge of doing that, when they located me.'

'Lucky for you – and for us. You may be able to throw light on many things we don't know.'

'Frankly, I doubt it – but I'll do my best. I don't remember a thing after that runaway space-pod charged me. Though I still find it hard to believe, I've been told that Hal was responsible.'

'That's true, but it's a complicated story. Everything we've been able to learn is in this recording – about twenty hours, but you can probably Fast most of it.'

'You know, of course, that Dave Bowman went out in the Number 2 Pod to rescue you – but was then locked outside the ship because Hal refused to open the pod-bay doors.'

'Why, for God's sake?'

Dr Kim winced slightly. It was not the first time Poole had noticed such a reaction.

(Must watch my language, he thought. 'God' seems to be a dirty word in this culture – must ask Indra about it.)

'There was a major programming error in Hal's instructions – he'd been given control of aspects of the mission you and Bowman didn't know about, it's all in the recording...

'Anyway, he also cut off the life-support systems to the three hybernauts – the Alpha Crew – and Bowman had to jettison their bodies as well.'

(So Dave and I were the Beta Crew – something else I didn't know...)

'What happened to them?' Poole asked. 'Couldn't they have been rescued, just as I was?'

'I'm afraid not: we've looked into it, of course. Bowman ejected them several hours after he'd taken back control from Hal, so their orbits were slightly different from yours. Just enough for them to burn up in Jupiter – while you skimmed by, and got a gravity boost that would have taken you to the Orion Nebula in a few thousand more years...'

'Doing everything on manual override – really a fantastic performance! – Bowman managed to get Discovery into orbit round Jupiter. And there he encountered what the Second Expedition called Big Brother – an apparent twin of the Tycho Monolith, but hundreds of times larger.'

'And that's where we lost him. He left Discovery in the remaining space-pod, and made a rendezvous with Big Brother. For almost a thousand years, we've been haunted by his last message: "By Deus – it's full of stars!"

(Here we go again! Poole told himself. No way Dave could have said that... Must have been 'My God – it's full of stars!')

'Apparently the pod was drawn into the Monolith by some kind of inertial field, because it – and presumably Bowman – survived an acceleration which should have crushed them instantly. And that was the last information anyone had, for almost ten years, until the joint US-Russian Leonov mission...'

'Which made a rendezvous with the abandoned Discovery so that Dr Chandra could go aboard and reactivate Hal. Yes, I know that.'

Dr Kim looked slightly embarrassed.

'Sorry – I wasn't sure how much you'd been told already Anyway, that's when even stranger things started to happen.'

'Apparently the arrival of Leonov triggered something inside Big Brother. If we did not have these recordings, no one would have believed what happened. Let me show you... here's Dr Heywood Floyd keeping the midnight watch aboard Discovery, after power had been restored. Of course you'll recognize everything.'

(Indeed I do: and how strange to see the long-dead Heywood Floyd, sitting in my old seat with Hal's unblinking red eye surveying everything in sight. And even stranger to think that Hal and I have both shared the same experience of resurrection from the dead...)

A message was coining up on one of the monitors, and Floyd answered lazily, 'OK, Hal. Who is calling?'

NO IDENTIFICATION.

Floyd looked slightly annoyed.

'Very well. Please give me the message.'

IT IS DANGEROUS TO REMAIN HERE. YOU MUST LEAVE WITHIN FIFTEEN DAYS.

'That is absolutely impossible. Our launch window does not open until twenty-six days from now. We do not have sufficient propellant for an earlier departure.'

I AM AWARE OF THESE FACTS. NEVERTHELESS YOU MUST LEAVE WITHIN FWFEEN DAYS.

'I cannot take this warning seriously unless I know its origin... who is speaking to me?'

I WAS DAVID BOWMAN. IT IS IMPORTANT THAT YOU BELIEVE ME. LOOK BEHIND YOU.

Heywood Floyd slowly turned in his swivel chair, away from the banked panels and switches of the computer display, towards the Velcro-covered catwalk behind.

('Watch this carefully,' said Dr Kim.

As if I needed telling, thought Poole...)

The zero-gravity environment of Discovery's observation deck was much dustier than he remembered it: he guessed that the air-filtration plant had not yet been brought on line. The parallel rays of the distant yet still brilliant Sun, streaming through the great windows, lit up a myriad of dancing motes in a classic display of Brownian movement.

And now something strange was happening to these particles of dust; some force seemed to be marshalling them, herding them away from a central point yet bringing others towards it, until they all met on the surface of a hollow sphere. That sphere, about a metre across, hovered in the air for a moment like a giant soap bubble. Then it elongated into an ellipsoid, whose surface began to pucker, to form folds and indentations. Poole was not really surprised when it started to assume the shape of a man.

He had seen such figures, blown out of glass, in museums and science exibitions. But this dusty phantom did not even approximate anatomical accuracy; it was like a crude clay figurine, or one of the primitive works of art found in the recesses of Stone Age caves. Only the head was fashioned with care; and the face, beyond all shadow of doubt, was that of Commander David Bowman.

HELLO, DR FLOYD. NOW DO YOU BELIEVE ME?

The lips of the figure never moved: Poole realized that the voice – yes, certainly Bowman's voice – was actually coming from the speaker grille.

THIS IS VERY DIFFICULT FOR ME, AND I HAVE LIITLE TIME. I HAVE BEEN ALLOWED TO GIVE THIS WARNING. YOU HAVE ONLY FIFFEEN DAYS.

'Why – and what are you?'

But the ghostly figure was already fading, its grainy envelope beginning to dissolve back into the constituent particles of dust.

GOOD-BYE, DOCTOR FLOYD. WE CAN HAVE NO FURTHER CONTACT. BUT THERE MAY BE ONE MORE MESSAGE, IF ALL GOES WELL.

As the image dissolved, Poole could not help smiling at that old Space Age cliche´. 'If all goes well' – how many times he had heard that phrase intoned before a mission!

The phantom vanished: only the motes of dancing dust were left, resuming their random patterns in the air. With an effort of will, Poole came back to the present.

'Well, Commander – what do you think of that?' asked Kim.